Which factors can negatively impact fuel efficiency?

The factors that can negatively impact fuel efficiency include tire pressure and engine tuning. Proper tire pressure is crucial because under-inflated tires create more rolling resistance, which means the engine has to work harder to move the vehicle, leading to reduced fuel efficiency. Additionally, if the engine is not properly tuned, it can run inefficiently, wasting fuel and producing higher emissions. A poorly tuned engine may have issues such as incorrect air-fuel mixture, malfunctioning sensors, or dirty fuel injectors that can all contribute to increased fuel consumption.

Consistent driving speed can actually enhance fuel efficiency by reducing unnecessary acceleration and braking, while high oil levels typically do not significantly impact fuel economy, and using premium fuel does not necessarily equate to improved fuel efficiency unless the engine requires it for optimal performance.